DESCRIPTION: (Applicant's Abstract) The long-term research interest in our laboratory has been the analysis of synaptic organization, neurochemical anatomy, and ontogeny of circuits involved in the control of movement. Studies have focused on the developmental expression and adult distribution of several peptides in one of the primary centers of motor control, the cerebellum. In the present proposal we will continue our studies which are designed to determine the role of peptides in regulating the development of cerebellar circuits. It is our hypothesis that the peptide corticotropin releasing factor (CRF) functions as a regulatory factor during the ontogeny of cerebellar circuits. The Specific Aims of this proposal are: 1) To determine temporal and spatial expression of CRF in cerebellar afferents, and CRF binding sites in the cerebellum. Immunohistochemical techniques will be used to analyze the ontogeny of CRF afferents in the cerebellum. Immunohistochemical techniques will be used to analyze the ontogeny of CRF afferents in the cerebellum. In addition, an mRNA probe for CRF will be used to identify possible brainstem source(s) of CRF-containing afferents at different ages. Autoradiographic techniques will be used to identify CRF binding sites in the cerebella of developing animals. These data will provide a developmental timetable for CRF and CRF binding sites requisite for interpretation of data derived in Specific Aims 2, 3 and 4. 2) To determine the temporal sequence in which cerebellar neurons express mRNA for the CRF receptor. Probes for the CRF receptor mRNA will be used to identify when different cerebellar neurons express message for the CRF receptor. These data will be compared and correlated with that obtained in Specific Aims 1 and 3. 3) To determine when axon terminals contain CRF, and make synaptic contacts on Purkinje cells in the developing cerebellum. Combined immunohistochemical and electron microscopic techniques will be used to address this question. 4) To determine when CRF fist alters the responsiveness of Purkinje cells in the developing cerebellum. Physiological and iontophoretic techniques will be carried out in slice preparations of the developing and adult cerebellum. The effects of CRF on spontaneous and amino acid induced responses will be compared at different ages. Thus, immunohistochemical, receptor binding , in situ hybridization histochemistry, electron microscopic and physiological experiments will be carried out to more precisely define the role of CRF in the developing cerebellum. The cerebellum is a critical component of circuits that control and co-ordinate movement. The abnormal expression of chemical signals during development could alter the activity of neurons, and their circuits which could be reflected as changes in motor performance in developing and/or adult animals. An understanding of the function of neuropeptides in the cerebellum may lead to the design of pharmacological therapies for the treatment of motor disorders (e.g., ataxia, tremor).